Exhaust aftertreatment systems may be provided in vehicles for the purpose of reducing nitrogen oxides (NOx) contained in exhaust gases discharged from the combustion chambers of internal combustion engines. In certain exhaust aftertreatment systems, a reductant may be injected into flow of exhaust. The reductant may be liquid urea that are injected as liquid droplets. Liquid urea may be injected at various positions, such as in the center of a straight segment of an exhaust conduit or at an elbow pipe in the exhaust conduit.
Effective reduction of NOx is dependent on a proper mixing of the urea droplets with the exhaust gas. Accumulation of urea deposits may hinder the proper mixing urea and exhaust gas. Further, spray distribution may be dependent upon the flow condition of the exhaust gas. Increased deposit at the injector tip during low exhaust flow conditions may reduce the spray distribution of the urea droplets. In particular, with in-elbow pipe injection systems, spray distribution variation may be greatly affected by exhaust flow conditions resulting in deposit issues at an elbow bend.
U.S. Pat. No. 8,899,022B2 discloses an exhaust gas aftertreatment device having a bent exhaust pipe, a mixing pipe with a closed end at the exhaust pipe bend and a bell-shaped widened portion in at least partial contact with the exhaust pipe at its opposite end, and a urea nozzle connected to a receptacle in the mixing pipe closed end for injecting an additive into exhaust gases. The exhaust gas flowing into the mixing pipe may flow through the perforations in the mixing pipe jacket. Part of the exhaust gases flowing into the perforations in the pipe jacket leads to a concentration of the exhaust gas flow at the centre mixing pipe.
CN103573351A discloses a mixing device for the aftertreatment of exhaust gases in an exhaust system of an internal combustion engine. The mixing device comprises a housing with an entrance opening having an inlet and an inner tube arranged inside the housing. The inner tube has a mixing region formed therein. A metering device is arranged on an end face of the housing to supply a liquid and/or a liquid-gas mixture. The inner tube, on its lateral surface, is provided with access openings through which the exhaust gases are introduced into the mixing region. Guide members are provided at respective openings. The guide members direct the flow of exhaust into the mixing region.
The present disclosure is directed, at least in part, to improving or overcoming one or more aspects of the prior art system.